A cooled gear housing includes a first casing section and a second casing section joined together to define an internal volume of the gear housing assembly. A heat conducting membrane is arranged within the gear housing assembly to hydraulically separate a first portion of the internal volume from a second portion of the internal volume. Two or more meshed gears are located within the first portion of the internal volume. Coolant inlet and outlet ports are arranged on one of the casing sections, and are in fluid communication with the second portion of the internal volume.